This is very strange. I just checked
http://www.diamondpet.com/ and it reiterates that no wheat gluten or rice protein concentrate is used in any Diamond canned, dry, or treats. Same message is on
http://www.chickensoupforthepetloverssoul.com/ It was one thing for Natural Balance to leave the ingredient out; but I don't think Diamond/Chicken Soup would legally get away with denying it was an ingredient like this. So, I believe them.